Electromagnetic sound pick-up

ABSTRACT

A sound pick-up for stereo sound reproduction with 90* phase shift between channels in which the armature structure is cylindrical centrally and quadilateral in the remaining parts of its length.

Unite States Patent 1191 Kiihn [45] Dec. 9, 1975 ELECTROMAGNETIC SOUND PICK-UP [75] Inventor: Hans-Rbert Kuhn, Kiel, Germany References Cited 73 Assignee: Electroacustic GmbH Kiel, Kiel, UNITED STATES PATENTS Germany 3,463,889 8/1969 'Ahrens l79/100.4I K 3,576,955 /1971 Obata 179/100.41 K [22] Flled: June 1, 1973 3,763,335 /1973 Morita 179/10041 K [21] Appl. No.: 365,841

Primary Examiner-Daryl W. Cook [44] gubhshed under thezgrrlagl7glolugtary Protest Assistant Examiner stewart Levy rogram on anuary as ocument Attorney, Agent, or Firm-Herbert L. Lerner B 365 ,84l'

[ Foreign Application Priority Data [571 ABSTRACT July 20, 1972 Germany 2235484 A sound pick-up for stereo sound reproduction with phase shift between channels in which the arma- [52] US. Cl. 179/100.41 K; 179/ 100.41 M; ture structure is cylindrical centrally and quadilateral 274/37 in the remaining parts of its length. [51] Int. Cl. H04R 11/12 58 Field of Search 179/10041 K, 100.41 D, 2 Clams, 2 Drawmg figures US. Patent Dec. 9, 1975 ELECTROMAGNETIC SOUND PICK-UP The invention relates to an electromagnetic sound pickup, preferably for reproduction of stereo sound with 90 phase shift matrixing between individual channels, wherein an armature fixed to the needle carrier is elastically flexible between the ends of two pole shoes and with the same flexibility in all flex directions.

Such an arrangement is especially needed forthe above mentioned stereo sound reproduction since the needle, and with it also the armature, follows a circular motion because of the 90 phase shift between the individual channels. Differential flexibility of the mounting in the individual flex directions of the armature would give rise to distortions in the reproduction of these stereo systems.

In reproduction with present day conventional stereo sound systems, an equal flexibility of the mounting in all flex directions of the armature is not necessarily needed, since the amplitudes and phase relations are r such that, with 180 phase shift of a stereo channel, the maximum amplitudes, which corresponds to the direct or middle sounds, cause a parallel horizontal flexing of the needle carrier on the record upper surface. Vertical flexing of the needle carrier occurring here, which is for the side sounds, are kept relatively small compared to the horizontal amplitudes, so that possible distortions are negligible, these arising from deflection of the needle carrier in a direction resulting from both main deflections, where the needle carrier can have different flexibility resistance or stiffness in the both main deflection directions.

Sound pick-ups with armatures of cylindrical cross section are known. A cylindrical cross section has the advantage that the armature has a uniform stiffness or deflection resistance in all directions of deflection, however, in contrast to a quadrilateral cross section, the disadvantage that, with it, the effective air gap between armature and the pick-up pole shoe ends is greater. By contrast, an armature with quadrilateral cross section can, without more, be positioned so that it has the completely equal stiffness or deflection resistance in all deflection directions.

The object of the invention is, therefore, to provide a sound pick-up with the advantages of armatures of cylindrical cross section and those of armatures with quadrilateral cross section combined. According to the invention, this is accomplished by constructing the armature cross section cylindrically in the region of its mounting, and quadrilaterally in the remaining part of its length.

In an inventive embodiment meeting the purpose, it is proposed that the armature be formed of two parts of quadrilateral cross section with bores in the lengthwise direction, these being separated from each other by the breadth of the armature support on the free end of the needle carrier which is cylindrical at least in the region of the width of the armature mounting.

The invention will be explained further in the following embodiments shown in the drawing.

DRAWINGS The FIGS. 1 and 2 show two different embodiments of armatures constructed in accordance with the invention. Corresponding parts-of both figures are shown by identical numerals.

PREFERRED EMBODIMENT FIG. 1 depicts a single piece armature l which has the needle holder 2 with the needle 3. The central region in which the armature l is to be mounted, is

cylindrical and its both ends are quadrilaterally formed. The armature support 4 is made of elastic material, and so without difficulty can be slid over the quadrilateral end of armature 1 to the central mounting region without difficulty.

In FIG. 2, a three piece armature 1 comprises the both quadrilateral partial pieces 1a and lb, which are bored through in their lengthwise directions. Both these partial pieces 1a and 1b are slid on and secured on the free cylindrical end of the needle holder 2 of cylindrical cross section and separated from each other as shown. Before the partial piece 1b is slid on the needle carrier 2, the armature support 4 is slid on needle carrier 2.

In operation, the armature can flex equally well in all directions in its cylindrical mounting 4. However, since the conventional existing pole shoes of a conventional magnetic pick-up are mounted over a quadrilateral portion of the armature, the pole shoes may be mounted with a smaller effective air gap than if the pole shoes of the pick-up were mounted over a cylindrical armature. The pick-up shoes may be as shown in US. Pat. No. 3,463,889, which shows a square armature.

FIG. 2 shows a three piece embodiment of the invention which operates in the same manner as the embodiment of FIG. 1.

I claim:

1. An electromagnetic sound pick-up armature for reproduction of stereo sound signals having phase shift between individual channels comprising an armature. secured to a needle carrier, said armature being elastically deflectable with uniform stiffness in all deflection directions, the cross section of the armature being cylindrical in the region of its mounting and quadrilateral in the part of its length, which is adapted to be inserted between the ends of two pole shoes of a magnetic pick-up.

2. A pick-up armature as in claim 1, having a three piece construction comprising a cylindrical piece and two spaced quadrilateral pieces mounted on said cylindrical piece. 

1. An electromagnetic sound pick-up armature for reproduction of stereo sound signals having 90* phase shift between individual channels comprising an armature secured to a needle carrier, said armature being elastically deflectable with uniform stiffness in all deflection directions, the cross section of the armature being cylindrical in the region of its mounting and quadrilateral in the part of its length, which is adapted to be inserted between the ends of two pole shoes of a magnetic pick-up.
 2. A pick-up armature as in claim 1, having a three piece construction comprising a cylindrical piece and two spaced quadrilateral pieces mounted on said cylindrical piece. 